For efficient use of electric power, it is desirable to match demand and supply of electric power with each other. Generally, a supply electric energy is determined in accordance with a demand forecast of electric power.
For example, as methods for determining a supply electric energy in accordance with a demand forecast of electric power, there are unit commitment which determines an economically low-cost power supply schedule by using hourly ON/OFF switching individual generators, and the like.
On the other hand, in recent years, there has been an increase of electric power generation using renewable energy, such as solar cell generation and wind power generation. In those generation methods, the power generation amount is difficult to control. In that case, it is difficult to achieve a demand-supply balance of electric power by general methods.
One of means for solving those problems is demand response which performs suppression and encouragement of electric power demand from consumers' device, by means of external signals.
In particular, stationary storage batteries expected to be widely used in the near future have a large charge/discharge power per battery, and accordingly are regarded as promising means which securely bring about an effect of demand response when charge and discharge time periods of a large number of stationary storage batteries are properly shifted.
For example, Patent Literature 1 (PTL 1) describes a direct load control system explained below. In the system, an electric power consumption rate γ=(pfut-pmin)/(pmax-pmin) is calculated for a plurality of controllable loads. Here, pfut is an average of future power consumption, pmax a maximum power consumption, and pmin a minimum power consumption. Based on the power consumption rate γ for each of the controllable loads, a grid operation apparatus produces a histogram representing distribution of a margin of increase pmax-p and a margin of decrease pmin-p in terms of change in γ. From the produced histogram, a maximization threshold value yon and a minimization threshold value γoff are calculated. Power consumption p of a controllable load is decreased to the minimum power consumption pmin of the controllable load when the power consumption rate γ of the controllable load is smaller than γoff, and on the contrary, power consumption p of the controllable load is increased to the maximum power consumption pmax when the power consumption rate γ of the controllable load is larger than yon.
For example, Patent Literature 2 (PTL 2) describes a method which assumes batteries of electric cars to be distributed electric power resources and controls electric power demand of the whole batteries by ON/OFF switching of charge (discharge) of the plurality of electric power resources.
Further, Patent Literature 3 (PTL 3) customizes a charge profile with respect to an energy storage device installed on an electric locomotive. It thereby aims at improving the operation life of the device and reducing the failure rate. However, PTL 3 aims at life improvement and failure rate reduction in an energy storage device connected to a single load, but does not perform demand-supply adjustment of electric power on a plurality of load, and does not perform demand response either.
Further, Patent Literature 4 (PTL 4) describes a storage battery management system for managing a plurality of storage battery units. The management system sets operation modes (a load follow-up mode, a life priority mode, a standby time priority mode, and the like) of the storage battery units in accordance with a purpose of use of the storage battery unit group. It weights the plurality of operation modes, thereby sets an evaluation function for evaluating a charge/discharge schedule of each of the storage battery units and, based on the evaluation function, individually determines the charge/discharge schedule of each of the storage battery units. However, PTL 4 does not perform demand response.